Sound-amplifying horn for gramophones, loud speakers, and other like sound-reproducing apparatus



.J. CULLUM Oct. 16, 1928.

SOUND AMPLIFYING HORN FOR GRAMOPHONES, LOUD SPEAKERS, AND OTHER LIKESOUND REPRODUCING APPARATUS Filed Nov. 17, 1926 1n nection withcabinets.

Patented a. 16, 1928.

UNITED/STATES PATENT OFFICE.

HENRY J'OHN' OULL'UM, OF LON DON ENGLAND.

sounn-mrnmyme norm ron GRAMOPHONES, noun SPEAKERS, AND ornna LIKE Ysounn-marnonucme APPARATUS.

1 j Application filed November 17; 1926, Serial No. 148,932, ad in GreatBritain May a1, 1926. i

This invention refers to improvements in or relating to sound amplifyinghorns for gramophones, loud speakers, and other like sound-reproducingapparatus, and it has for 5 its object to provide a horn'of improved andsimplified construction which will give a maximum of length for a givenoverall size, thus rendering the improved horn especially suitable forbuilding into or for use in conportable gramophone and like Nowaccording to the present invention th improved sound amplifying horn,which is preferably built up from sheet metal, fibre, wood or' othermaterial, is of zigzagged or sinuous formation so that the sides of thevarious straight portions of the horn can be closely nested together toefiect economy in space and so that the partition walls can each be madecommon to twdstraight portions of the horn to effect an improvement inthe reso nance of the horn and economy in material.

i In order that the present invention may be clearly understood and morereadily car- -ried into effect, it is hereinafter described withreference to the accompanying drawings, in which v Figure 1 is a planview of a sound amplifying horn, specially constructed for use inconnection with a portable gramophone;

Figure 2, is a side elevation'thereof, and

Figure 3 is an end elevation thereof.

Preferably the horn is as, shown formed with one side a, which may formthe bottom,

flat, or horizontal, andthe other side I) shaped and bent so as toprovide inclined or gradually rising sides or upper portions to thevarious sections 0,03, 6, f, of the horn. It is not, however,essentia lthat one side should 40 be entirely flat, although this is preferablewhere the 'horn 'is to be'used in a horizontal position.- Inother-case's it may be found more convenient to arrange the horn in avertical 'plane and to shape both sides so that all sections of the:horn can be kept in one medial plane. In the case, however, of aportable gramophone, the arrangement first described will be found to bemost convenient, owing to the fact; that the. smaller sections such as0, (Land e of the'horn provide the space necessary for the accommodationof the motor andfor the swivelling portion of the tone-arm In one of thesimplest forms of construc- 155 tion shownin'thefdrawings, the lower-orbase with an upstanding flange or wall it of vary- Y ingheight, andalso, in the case of a foursection horn 0, d, e, f, with threeintermediate partition walls, 2', j and k which extend alternatelyinwards from opposite sides and serve to divide the base portion up intothe four sections 0, d, e, f, The partition walls 2', j, is, merge intothe-marginal walls or flanges h of the lower base portion a and also 7are of varying heights such as are required to give the requiredgradually increasing area to the amplifying horn. The base a, to e whichthe outer walls h of the horn are soldered or otherwise secured, may beof the I exact shape or outline of the horn, though I prefer tosuperimpose these walls It upon a base of larger size its shown) whichis pierced with suitable oles at for enabling same tobe fixed rigidly toa board forming part ofa gramophone case. The purpose of this is twofoldin that it enables the horn to be built into its cabinet in properalignl'nent and in that it enables metallic sounds to be moreefl'ectively damped out by the-placing of suitable absorbent ornon-sound con'ductand it-reseinbles in appearance a zlgzagged risingpathway, starting from the smaller or 100 tdne arm end m of the soundamplifying horn and gradually rising until it stops short of theupturned and rounded end n of the bottom plate a to provide an upwardexit opening 0. In ,some'cas es where the sound is to lotbe projectedoutwards and not upwards (as shown), the upper portion 6 may be made toextend to a: line parallel and coextensive with the base member a, orthe exit opening may be arranged wholly or partially in the plane 110 ofthe horn. One of the partition walls 71 and also a portion of the outerupstanding side Wall of the lower plate'are shaped as at h to co-operatewith the curved or upwardly flared portion 9 of the horn. At the turnsor bends at the ends of the horn sections, the upstanding side wall hprovidedon the ldwer plate is preferably bent at an angle or V as bestshown in Figures 1 and 2 so as to pro vide a better reflecting surfacefor the sound waves and to prevent their being pocketed, whilst the freeinner ends of the partition walls z, j and is, may also be slightlycurved or rounded as shown at go so as to ensure that the sound waveswill be slightly compressed gr retarded just before they pass the turnor end.

Another important feature of the im proved zigzag hornwhich contributeslargely to its rigidity of construction and purity of tone is thearrangement whereby the gradually enlarging sections of the horn areconnected together to the three intermediate partition walls, that is tosay, the edge of the inclined roof of each zigzag section on that sideof the division wall toward the entrant end of the horn is secured-totheside of the division wall below the upper edge and gradually inclinesupwardly and finally is secured to the upper edge of the division wall.a This construction forms a powerful stay whichstrengthens the wall andto a great extent prevents vibration or repercussion which may occur onone wall first-of all and then on the other side thereof as the soundwave traverses the passage way.

It will be seen that by the-present invention, I am enabled to constructan extremely portable horn in a simple, strong and workmanlike mannerfrom flat steel material, and that it is readily? possible to provide ahorn constructed of different materials, according to the quality of thetone required which is not possible in the case of horns of circularcross section. For instance, the base portion a can be made'of metal andthe upper portion 6 of wood, fibre or other material designed to efi'ectany desired variation in the tonal quality of" the sound. Further, I amenabled to provide a horn containing a flare of accurate dimensions inits gradual enlargement from the smallest to largest diameter or squareand by the utilization of a common wall or division nested in zigzagfashion, I secure an increase in horn length of 30 per centwithin anygiven space over the ordinary self-contained sinuous type of'h'orn. WhatI claim is 1. A sound amplifying horn constructed on uninterrupted sidewalls and edge walls, said edge walls being of gradually increasedheight from the entrant end of the horn, and division walls of graduallyincreased height projecting inwardly from opposite edge wallssuccessively from the entrant to the exit end of thehorn, the divisionwalls being secured throughout their lengths to the side walls. 2. Asound amplifying horn constructed of uninterrupted side walls and edgewalls, and division walls projecting inwardly from opposite edge wallssuccessively from the entrantto the exit end of the horn, the divisionwalls secured throughout their lengths to the side walls and beingincreasingly spaced apart from the entrant to the exit end of the horn,one of the side walls being increasingly spaced from the other from theentrant end of the horn. I

3. A sound amplifying horn constructed ,of sheet material and comprisingtwo side walls, spaced edge walls secured to and between the side walls,division walls projecting alternately from the op osite edge walls andsecured throughout their lengths to one of the side walls, the other ofthe side walls being slitted in line with the division walls to permit aportion of such slitted side wall to be secured to a division wall at anupward said wall while permitting the immediately adjacent slittedportion of the side wall to be secured to the upper edge of the divisionwall. 7

4. A sound amplifying horn comprising a sound amplifying space definedby side walls and edge walls, one of the side walls being formed topresent a sinuous path throughout which the said side wall inclinesincreasingly upward relative to the other side wall, and division wallsarranged interiorly of the space and defining with the inclined portionof the side wall a tortuous passage of gradually increasing area fromthe entrant end of the horn.

5. A sound amplifying horn comprising spaced side walls connected byedge walls to define a sound amplifying space, a series of partitionssecured alternately to the respective edge walls and projectingtowardand terminating short of the opposite edge wall,

' said partitions being increasingly spaced apart from the entrant endof the horn to define a tortuous passage in the sound amplifying space,each edge wall opposite the free the sound om one side of the divisionwall to the opposite side in the direction" of sound a travel.

In testimony whereof I have hereunto signed my name.

- HENRY JOHN CULLUM.

